Thiophenol → 5-Phenylthiophene-3-carboxylic acid

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Reaction Conditions

Reaction Steps

In an open flask, thiophenol (2.86 g., 13 mmoles), cuprous oxide (1.86 g., 13 mmoles) and dimethyl formamide (30 ml.) were combined and heated in a 135° C. oil bath. The reaction mixture was allowed to cool slightly, 5-bromothiophene-3-carboxylic acid [2.5 g., 13 mmoles; Fournari et al., Bull. Chim. Soc. Fr., 4115 (1967)] in 50 ml. of dimethylformamide was added, and the mixture refluxed for 2 days. The reaction mixture was cooled, clarified by filtration, the filtrate evaporated to an oil, the oil triturated with 1 N hydrochloric acid, and gummy solids recovered by filtration and taken up in 1 N sodium hydroxide. The basic solution was extracted with ether, reacidified with conc. hydrochloric acid, product recovered by filtration, triturated with hexane and refiltered (912 mg., m.p. 97°-100° C., m/e 220). Recrystallization from methanol/water afforded purified 5-phenylthiofuran-3-carboxylic acid (439 mg., m.p. 101°-103° C.).

Provenance & Evidence